BETHPAGE - The National Transportation Safety Board has joined the investigation into Sunday's fatal plane crash in Bethpage.

The single-engine plane had taken off from Francis S. Gabreski Airport in the Town of Southampton and was headed to New Jersey. The plane reported that it was experiencing difficulties. It went down shortly before 8 a.m. on the LIRR tracks at a rail crossing -- just across from the building that houses the headquarters of mattress retailer Sleepy's.

The pilot's widow has identified him as Joseph Milo, of Westhampton Beach. He was the owner of Joe's American Grill on Montauk Highway for more than 35 years.

News 12 has learned that the NTSB is investigating whether an air traffic controller at LaGuardia Airport may have guided the pilot to land at a runway that no longer exists.

Audio of the controller was made available through website LiveATC.net. In the recording, the controller appears to repeatedly tell the pilot that he could land on an old, unused runway at Northrop Grumman's Bethpage plant. That airport closed in 1985, and its runway no longer exists. The pilot is not audible in the recording.

Sources tell News 12 that the Federal Aviation Administration is in the process of handing over the full air traffic control recording to the NTSB.

Some aviation experts say that while air traffic controllers can make suggestions and give advice, it is ultimately up to the pilot to decide where to land the plane.

"He's accountable for the navigation, so that pilot needed to be up in the air with the proper up-to-date maps so he could make those decisions, especially in an emergency," says Col. Michael Canders, of the Farmingdale State College aviation department.

NTSB investigator Dan Boggs says the agency expects to complete its on-site investigation within the next few days. He says a preliminary report should be available within a week.